Micronecta (Unguinecta), 2005

Nieser, Nico, Chen, Ping-ping & Yang, Chang Man, 2005, A New Subgenus And Six New Species Of Nepomorpha (Insecta: Heteroptera) From Yunnan, China, Raffles Bulletin of Zoology 53 (2), pp. 189-209 : 200-202

Micronecta (Unguinecta) , new subgenus

Type species. – Micronecta polhemusi Nieser, 2000 .

Description. – Medium sized Micronecta . Length, males 2.1- 2.8, females 2.5-3.0; rostrum with transverse sulcations; ocelli

absent; antennae three segmented, with the last segment largest and swollen; pronotum posteriorly convex; scutellum exposed; hemielytra with sparse pale pubescence, embolar groove without nodal furrow; fore tibia and pala in males separate, in females fused; in both sexes, apical bristle of ventral palar row strongly developed into a secondary claw on the pala ( Fig. 50 ); claw of hind leg placed apically on tarsal segment two; seventh abdominal sternite with two stout long hairs. Male: prestrigilar lobe with a broadly rounded medial apex ( Fig. 46 ); strigil present; free lobe of left part of segment eight with a slightly produced laterocaudal angle and left parameres with a long and narrow, apically tapering shaft ( Fig. 43 ). Usually dark coloured except for M. waltoniana . Males have a row of small spines along ventral (flexor) margin of the fore femur except for M. khasiensis . Moreover, the right parameres have a generally similar shape with a slightly curved, over most of its length more or less parallel, shaft with an obtusely pointed apex.

Species included. – Micronecta (Unguinecta) polhemusi Nieser, 2000 , from Thailand and the Malay Peninsula (type species); M. (U.) khasiensis Hutchinson, 1940 , from India (Assam) and Vietnam; M. (U.) matsumurai Miyamoto, 1965 , from China (Taiwan); M. (U.) melanochroa , new species,

from China (Yunnan); and M. (U.) waltoniana Hutchinson, 1940 from India (Assam).

Etymology. – Unguinecta [unguis (Latin: nail or claw) + necta (Greek suffix: swimmer)], means “clawed swimmer”, referring to the distinctly developed secondary claw on the pala.

Discussion. – In Micronecta the truly reliable characters for specific identification and delimitation of subgenera are the male sexual characters, which will be emphasized below.

Poisson (1938) established the monotypic subgenus Mesonecta to include Micronecta (Mesonecta) pilosa Poisson, 1938 from Madagascar. Mesonecta was based on the following characters: claw of male pala flanked with a secondary claw; free lobe of left part of segment eight evenly rounded apically; both parameres with sharp apical points. Hutchinson (1940) added M. khasiensis and M. waltoniana to the subgenus Mesonecta without indicating on which characters the classification was based. However, in his key to subgenera he mentioned the characters of the secondary palar claw, inner angle of free lobe of left part of tergite VIII obtusely rounded, and seventh sternite with two large bristles, adding that the status of the last character is unknown in M. pilosa . Wróblewski (1962) pointed out that the only character connecting these three species is the secondary palar claw but left them in the subgenus Mesonecta .

In our opinion, Mesonecta has to be rectricted to its single original species, M. (M.) pilosa which differs from the subgenus Unguinecta in the following characters: The left paramere of M. pilosa has a broad, slightly sinuate shaft which has a wide truncate apex pointing to one side; the right paramere has a narrow, straight shaft with a sharply pointed apex; the free lobe of left part of segment eight is evenly rounded. Consequently in Mesonecta both parameres and the free lobe of left part of segment eight are of entirely different types compared to those of Unguinecta . In addition, M. pilosa has a light colour, a length of 4 mm, and its hemielytra are quite densely beset with black bristles, whereas the species of Unguinecta measure 2-3 mm and have sparse pale bristles on the hemielytra, except in M. polhemusi where the bristles are pale but more dense. Therefore, we conclude that Mesonecta is a different subgenus.

Yang (1967) described M. unguiculata from Taiwan in which the male also has a secondary palar claw. Compared to the species of Unguinecta , this species differs in being distinctly smaller (length of male 1.6); having a broad left paramere; a different type of prestrigilar lobe with an obtuse but distinct process pointing medially; and four large bristles on seventh abdominal sternite. In our opinion, in spite of the secondary palar claw, the four large bristles on seventh abdominal sternite and the male sexual characters place this species in subgenus Micronecta . Yang (1967) correctly placed M. unguiculata in the subgenus Micronecta . We consider that M. unguicula is closely related to M. (M.) lenticularis Chen, 1960 , which is commonly distributed in Taiwan, instead of M. matsumurai as indicated by Yang (1967).

Figures

Figs. 49-50. Micronecta melanochroa, new species, paratype, male; 49) foreleg; 50) apex of pala. Scale: 0.05 mm.

Figs. 42-48. Micronecta melanochroa, new species, paratype, male; 42) right paramere; 43) left paramere; 44) right part of tergite VI; 45) strigil, scale: 0.05 mm; 46) prestrigilar lobe; 47) mediocaudal lobe of sternite VII; 48) free lobe of left part of tergite VIII. Figs. 42-44, 46- 48, scale: 0.1 mm.